It is well known in the color photography art that color images are produced by a colored dye which is formed by a coupling reaction between an oxidized product of an aromatic primary amine color developing agent and a coupler. Various types of cyan, magenta and yellow dye-forming couplers are well known for use in such coupling reactions. The couplers are often used in combination with one or more solvents and/or other additives. For example, the Thirtle et al U.S. Pat. No. 2,835,579 discloses photographic emulsions comprising couplers in combination with alkylphenol or acylphenol coupler solvents. Similarly, Japanese Reference No. 61-075349 discloses photographic silver halide emulsion layers containing a coupler dissolved in a phenolic organic solvent having a high boiling point. The Aoki et al U.S. Pat. No. 4,686,177 discloses silver halide color photographic materials containing a cyan coupler which may be dissolved in an organic solvent. The resulting solution is finely dispersed in water or an aqueous binder for incorporation in the photographic material. Aoki et al broadly disclose numerous organic solvents which may be employed including, among others, alcohols and phenols. The Konishiroku Photo Industry European References Nos. 137,722, 143,570 and 145,342 similarly disclose silver halide color photographic materials which include at least one magenta coupler and a non-color forming phenolic compound such as a phenolic high-boiling organic solvent. Japanese reference No. 81-041098 discloses silver halide color photographic light sensitive materials prepared using cyan coupler compounds dispersed and emulsified in solvents having a boiling point greater than 200.degree. C. and saturated alcohols of the formula ROH wherein R is a 9 to 18 carbon containing saturated unbranched aliphatic group.
It is often desirable in color photography to provide the coupler compounds with improved coupler activity. As employed herein, the term improved coupler activity relates to the improved colorability of a coupler as indicated, for example, by the acceleration of the reaction of the coupler with the oxidized developer in forming the colored dye and/or by an increase in the color density of the resulting colored dye. For example, the Sasaki et al U.S. Pat. No. 4,774,166 broadly discloses numerous compounds for use as coloration accelerators for couplers which result in a reduction in the photographic processing time. Sasaki et al disclose that preferred coloration accelerators comprise phenolic compounds, oxyalkylene compounds and hydroxy substituted, 5- to 7- membered heterocyclic ring compounds.
Many coupler compositions, however, are disadvantageous in that relatively large amounts of a coupler are required to provide satisfactory color density, the reaction rate of the coupler with the oxidized developer is unacceptably low, the coupler exhibits unacceptably high sensitivity to the pH of the developer solution and/or the like. Accordingly, a continuing desire exists for coupler compositions of improved activity for use in color photographic materials and methods.